<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script type="text/javascript">
    /*
       基于Promise发送Ajax请求
     */
    function queryData(url) {
        var p = new Promise(function(resolve, reject){
            var xhr = new XMLHttpRequest();
            xhr.onreadystatechange = function(){
                if(xhr.readyState != 4) return;
                if(xhr.readyState == 4 && xhr.status == 200) {
                    // 处理正常的情况
                    resolve(xhr.responseText);
                }else{
                    // 处理异常情况
                    reject('服务器错误');
                }
            };
            xhr.open('get', url);
            xhr.send(null);
        });
        return p;
    }

    queryData('http://js.cn/api/index.php?p=1')
        .then(function(data){
            console.log(data)
            return queryData('http://js.cn/api/index.php?p='+data+1);
        })
        .then(function(data){
            console.log(data,456)
            return data;
        })
        .then(function(data){
            console.log(data,123)
        });

</script>

</body>
</html>